A dental prophylaxis procedure typically involves the application of an abrasive paste (i.e., a paste containing abrasive particles) to a tooth surface upon which pressure and rotational motion are applied. The removal of plaque, calculus and stains is facilitated by the resultant abrasion at the interface between the abrasive particles and tooth surface.
The pressure and rotational motion are applied to the abrasive paste by means of a prophy cup which comprises a cup-shaped element of about one-quarter inch diameter, the outer peripheral wall of which is elastically flexible. The cup is mounted on a drive shaft which rotates the cup at high speed, e.g., about 1,500-5000 rpm. An operator presses the cup against a tooth following the insertion of abrasive paste into the cup. The paste serves as a carrier, and the abrasives in the paste function to abrade away plaque, calculus, and stains from the tooth surfaces.
This procedure has traditionally exhibited certain shortcomings. For example, during the prophylaxis procedure, the paste becomes diluted when coming into contact with saliva, blood and/or water. Since the amount of paste contained in the cup is small, e.g., about 0.1 grams, even a slight dilution has a pronounced adverse effect on the concentration of abrasive particles. As dilution increases, abrasion and performance decreases.
Additionally, the centrifugal force generated by a prophy cup rotating at about 1,500-5000 rpm causes the paste to be displaced in a radial direction. The amount of paste retained at the interface of the cup and tooth surface after one second (25 rotations) is a small fraction of the initial volume. The decreased amount of paste results in reduced abrasion and performance.
The above-described shortcomings involve a reduced availability of abrasive at the working area. Additional shortcomings, however, relate to the geometry of the cup. In that regard, prophy cups are designed to be flexible. That is, as the operator presses the cup against a tooth surface, the outer annular rim of the cup is intended to flex outwardly in order to increase the area of surface contact between the cup and the tooth. However, that the amount of flexing exhibited by presently used cups results in a relatively narrow area of surface contact being established. That area is ring-shaped. This makes it difficult for the operator to control the magnitude and placement of abrasion.
If the cup rim were made thinner in order to increase its flexibility, then the outer portion of the rim may apply only weak forces to the abrasive particles, whereby the cleaning action is ineffective.
Furthermore, conventional dental prophy cups spread germs over the teeth. They are not designed to lift off the germs from the teeth. Therefore, it would be desirable to provide a dental prophy cup which minimizes or obviates the above-described shortcomings.